1. Field of the Invention
The present invention relates to internal liners or booties of ski boots and relates, more particularly, to liners whose adaptability to the foot of the skier is achieved by means of a product injected into at least one cavity with which the liners are provided and which corresponds to the tightening and/or retention zone of the foot.
2. Description of Background and Relevant Information
Ski boot liners of this type most often include a cavity or a pocket, defined by an external and an internal wall for injection of a filling product. At least the internal wall is relatively flexible and/or deformable to conform to the corresponding zone of the foot of skier under the effect of the pressure of the injected product. To ensure the optimum retention of the foot, various embodiments of liners and/or of adjustments of the foot in the boot have been proposed in the prior art. Thus, certain embodiments present, in particular, an integral adjustment of the internal wall of the liner around the foot, while other embodiments are directed, instead, towards the tightening zones on the foot.
Thus, for example, French Patent No. 2,056,381 describes a liner constituted by two envelopes nested within one another, the internal envelope being adapted to receive and to integrally envelope the foot, while the external envelope is adapted to adjust itself to the corresponding space provided in the boot. The injection of the product occurs after the introduction of the foot in the liner which makes it possible to obtain a tight application of the liner on the foot by ensuring, in particular, adjustment of the internal envelope to the morphology of the plantar surface of the skier. Such an adjustment is, however, sometimes the cause of certain discomforts such as cramps and numbness. In effect, due to the variations of the deformation of the foot under load being blocked in the plantar support zone, localized compressions occur on the portions of the foot subjected to the deformations, for example, lateral with respect to the front of the foot and vertical with respect to the instep and the plantar arch. It is likewise the case with the liner which forms the object of U.S. Pat. No. 4,182,056, in which the cavity, adapted to adjust itself to the foot, extends under the plantar surface of the foot.
Furthermore, both in the embodiment of the liner according to French Patent No. 2,056,381, as well as in the case of U.S. Pat. No. 4,182,056, the static position of the foot can be distorted during the injection if the skier rests more on the interior or on the exterior of the foot. In such a case, by virtue of the pressure and/or expansion of the injected product, the adjustment of the liner is then accentuated in the zones of the plantar surface upon which the skier does not rest or upon which the skier rests less than other zones.
Another embodiment of an adjustment of the foot in a liner is proposed in French Patent No. 1,412,280 which discloses the arrangement of a plurality of small cushions corresponding to the portions of the foot to be supported. The plantar zone of the foot is protected from an overly tight adjustment. On the other hand, such a construction of the support elements of the foot is relatively complicated by virtue of the plurality of small cushions. Furthermore, the small cushions are randomly removable and are not associable with the internal foot retention apparatus which are known, such as those described in French Patent No. 2,345,097 and PCT Published Application No. 7900770, for example.
French Patent No. 2,107,590 discloses a liner which includes a filling cavity which is positioned only on the rear portion of the foot, while the front portion of the liner is preshaped at its anterior and not subjected to the adjustment by injection in the cavity. The adaptation of such a liner to the foot of the skier occurs first by the shaping of the front portion, for example on a shoe tree, then by injection of the filling product in the cavity of the rear portion of the foot then introduced into the boot. This relatively careful adaptation process requires a plurality of manipulations requiring a certain non-negligible time for execution and, likewise, an elevated operational cost.